linux-kernel - Re: [PATCH] cpufreq: s3c64xx: Remove pointless NULL check in s3c64xx_cpufreq_driver

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Date:   Wed, 23 Oct 2019 09:26:28 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] cpufreq: s3c64xx: Remove pointless NULL check in
 s3c64xx_cpufreq_driver_init

On Wed, Oct 23, 2019 at 11:43:04AM +0100, Mark Brown wrote:
> On Wed, Oct 23, 2019 at 08:53:02AM +0530, Viresh Kumar wrote:
> > On 22-10-19, 17:09, Nathan Chancellor wrote:
> > > When building with Clang + -Wtautological-pointer-compare:
> > > 
> > > drivers/cpufreq/s3c64xx-cpufreq.c:152:6: warning: comparison of array
> > > 's3c64xx_freq_table' equal to a null pointer is always false
> > > [-Wtautological-pointer-compare]
> > >         if (s3c64xx_freq_table == NULL) {
> > >             ^~~~~~~~~~~~~~~~~~    ~~~~
> > > 1 warning generated.
> > > 
> > > The definition of s3c64xx_freq_table is surrounded by an ifdef
> > > directive for CONFIG_CPU_S3C6410, which is always true for this driver
> > > because it depends on it in drivers/cpufreq/Kconfig.arm (and if it
> > > weren't, there would be a build error because s3c64xx_freq_table would
> > > not be a defined symbol).
> 
> > +broonie, who wrote this patch to see his views on why he kept it like
> > this.
> 
> The driver should also have supported s3c6400 as well.

Kconfig says otherwise, unless I am missing something.

config ARM_S3C64XX_CPUFREQ
        bool "Samsung S3C64XX"
        depends on CPU_S3C6410
        default y
        help
          This adds the CPUFreq driver for Samsung S3C6410 SoC.

          If in doubt, say N.

Cheers,
Nathan